The present invention relates to a galvano-magneto effect device to be employed as a magneto-resistance effect device or Hall effect device.
The conventional galvano-magneto effect device as shown in FIG. 10 is made up by bonding a wafer made of a semiconductor material onto substrate 100, grinding said wafer, shaping the ground wafer in a specified form to make galvano-magneto effect element 101, connecting lead wires 102 to ends of said galvano-magneto effect element and fixing cover plate 103 made of a magnetic material such as ferrite on the center of element 101.
In case of such the device, cover plate 103 is directly bonded to the surface of a semiconductor layer of galvano-magneto effect element 101 and accordingly the galvano-magneto effect element may be damaged when securing the cover plate on the element. Since the lead wires are only bonded to the terminals of the galvano-magneto effect element, the lead wires may be disconnected or may come off from the bonded portions when the device is installed in an equipment or is transported.
Furthermore, in the conventional, device, substrate 100 is generally made in the thickness of approximately 0.5 mm to 1 mm; accordingly if the permissible thickness error of the substrate is 1 percent the maximum error of thickness is 5.mu. - 10.mu.. On the other hand, the thickness of the galvano-magneto effect element is generally 1.mu. to 20.mu.. It is known that the thinner the thickness of the element is, the better the Hall effect, that is, the galvano-magneto effect of the element becomes and therefore, the element is preferable to be as thin as possible. However, the element is generally made up by grinding the wafer to a thin thickness after fixing a thick semiconductor wafer on the substrate and the thickness of the element is obtained by measuring the thickness of the substrate and element which are joined. If the surface of the substrate is slanted, the thickness of the element is not uniform, or if the thickness of the substrates of a great number of devices is uneven, the thickness of the elements differs with the devices. Thus, the grinding accuracy of the element depends on the thickness accuracy of the substrate. Accordingly, in case of a thick substrate as described above, the maximum error of the thickness of the substrate is large and the irregularity in the thickness of the element becomes extremely large if it is necessary to make the element thin. For this reason, the thickness of the element cannot be fully controlled, the devices with uniform characteristic cannot be obtained and each device cannot have excellent characteristics.